Transition piece impingement sleeve for a gas turbine

ABSTRACT

An impingement sleeve for a transition piece of a gas turbine is disclosed. The impingement sleeve generally includes a first casing configured to surround a portion of an inner duct of the transition piece and a second casing configured to surround a portion of the inner duct. Additionally, the impingement sleeve may include a joint defined between the first and second casings. The joint may include a plurality of fasteners configured to attach the first casing to the second casing.

FIELD OF THE INVENTION

The present subject matter relates generally to gas turbines and, more particularly, to an impingement sleeve for a transition piece of a gas turbine combustor.

BACKGROUND OF THE INVENTION

Gas turbines typically include a compressor section, a combustion section, and a turbine section. The compressor section pressurizes air flowing into the turbine. The pressurized air discharged from the compressor section flows into the combustion section, which may be characterized by a plurality of combustors disposed around an annular array about the axis of the engine. Each of the plurality of combustors includes a combustion liner, which defines the combustion chamber of the combustor. As such, air entering each combustor is mixed with fuel and combusted within the combustion liner. Hot gases of combustion flow from the combustion liner through a transition piece to the turbine section of the gas turbine to drive the turbine and generate power.

The transition piece of a gas turbine may be configured as a double walled component. In particular, the transition piece may include an impingement sleeve and an inner duct disposed radially inwardly from the impingement sleeve. The inner duct is generally configured to transport the flow of hot gases from the combustion chamber to a first stage nozzle of the turbine section. The impingement sleeve is generally configured to provide impingement cooling for the inner duct. For example, the impingement sleeve may define a plurality cooling holes configured to receive the pressurized air discharged from the compressor section.

It is often the case that the geometry or shape of the inner duct necessitates that the impingement sleeve be formed from two or more sections configured to be assembled around the inner duct. Typically, the sections of the impingement sleeve are welded to one another. However, the process of welding the impingement sleeve sections together is often a difficult task. Moreover, by welding the sections to one another, the disassembly of the impingement sleeve in the field in order to perform inspections and/or repairs can be quite challenging and very time consuming.

Accordingly, an impingement sleeve that can be easily assembled and disassembled would be welcomed in the art.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect, the present subject matter discloses an impingement sleeve for a transition piece of a gas turbine. The impingement sleeve generally includes a first casing configured to surround a portion of an inner duct of the transition piece and a second casing configured to surround a portion of the inner duct. Additionally, the impingement sleeve may include a substantially flat joint defined between the first and second casings. The substantially flat joint may include a plurality of fasteners configured to attach the first casing to the second casing.

In another aspect, the present subject matter discloses an impingement sleeve for a transition piece of a gas turbine. The impingement sleeve generally includes a first casing configured to surround a portion of an inner duct of the transition piece and a second casing configured to surround a portion of the inner duct. Additionally, the impingement sleeve may include a joint defined between the first and second casings. The joint may include a plurality of fasteners configured to attach the first casing to the second casing. Further, at least one channel may be mounted to an inner surface of at least one of the first casing and the second casing. The channel may generally include a plurality of threaded nuts secured thereto.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 illustrates a schematic depiction of a gas turbine;

FIG. 2 illustrates a cross-sectional, side view of a combustor of a gas turbine;

FIG. 3 illustrates a perspective view of one embodiment of an impingement sleeve in accordance with aspects of the present subject matter;

FIG. 4 illustrates an exploded view of one embodiment of a double walled transition piece in accordance with aspects of the present subject matter;

FIG. 5 illustrates a cross-sectional, side view of the double walled transition piece shown in FIG. 4; and

FIG. 6 illustrates a partial, cross-sectional view of one embodiment of an attachment joint for attaching components of an impingement sleeve together in accordance with aspects of the present subject matter.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Referring to the drawings, FIG. 1 illustrates a schematic depiction of a gas turbine 10. The gas turbine 10 includes a compressor section 12, a combustion section 14, and a turbine section 16. The combustion section 14 may include a plurality of combustors 20 (one of which is illustrated in FIG. 2) disposed around an annular array about the axis of the gas turbine 10. The compressor section 12 and turbine section 16 may be coupled by a shaft 18. The shaft 18 may be a single shaft or a plurality of shaft segments coupled together to form the shaft 18. During operation of the gas turbine 10, the compressor section 12 supplies compressed air to the combustion section 14. The compressed air is mixed with fuel and burned within each combustor 20 (FIG. 2) and hot gases of combustion flow from the combustion section 14 to the turbine section 16, wherein energy is extracted from the hot gases to produce work.

Referring to FIG. 2, a cross-sectional side view of an embodiment of a combustor 20 of the combustion section 14 of a gas turbine 10 is illustrated. The combustor 20 may generally include a substantially cylindrical combustion casing 22 secured to a portion of a gas turbine casing 24, such as a compressor discharge casing or a combustion wrapper casing. A flange 26 may generally extend outwardly from an upstream end of the combustion casing 22. The flange 26 may be configured such that an end cover assembly (not illustrated) may be secured to the combustion casing 22. As is generally known, the end cover assembly may include a plurality of fuel nozzles (not shown).

The combustor 20 may also include an internal flow sleeve 28 and a combustion liner 30 substantially concentrically arranged within the flow sleeve 28. The combustion liner 30 may generally define a substantially cylindrical combustion chamber 32, wherein fuel and air are injected and combusted to produce hot gases of combustion. Additionally, both the flow sleeve 28 and the combustion liner 30 may extend, at their downstream ends, to a double walled transition piece 34, including an impingement sleeve 36 and an inner duct 38 disposed radially inwardly from the impingement sleeve 36. In particular, the combustion liner 30 may be coupled at its downstream end to the inner duct 38 such that the combustion liner 30 and the inner duct 38 generally define a flowpath for the hot gases of combustion flowing from each combustor 20 to the turbine section 16 of the gas turbine 10 (FIG. 1). Moreover, the flow sleeve 28 may be coupled at its downstream end to the impingement sleeve 36 such that the flow sleeve 28 and the impingement sleeve 36 generally define a flowpath for the pressurized air discharged from the compressor section 12 of the gas turbine 10 (FIG. 1). For example, the impingement sleeve 36 may define a plurality of cooling holes 40 configured to permit the pressurized air to enter the radial space defined between the inner duct 38 and the impingement sleeve 36.

Further, as shown in FIG. 2, one or both of the downstream ends of impingement sleeve 36 and the inner duct 38 may be coupled to a transition piece aft frame 42. As is generally understood, the aft frame 42 may be configured to attach the transition piece 34 to a first stage nozzle (not shown) of the turbine section 16 (FIG. 1) such that the hot gases of combustion flowing through the inner duct 38 may be directed into the turbine section 16.

Referring now to FIGS. 3-6, one embodiment of a double walled transition piece 100 and, particularly, one embodiment of an impingement sleeve 102 suitable for use with the transition piece 100 is illustrated in accordance with aspects of the present subject matter. In particular, FIG. 3 illustrates a perspective view of the impingement sleeve 102. FIGS. 4 and 5 illustrate exploded and cross-sectional views, respectively, of the transition piece 100, particularly illustrating various components and/or features of the impingement sleeve 102. Additionally, FIG. 6 illustrates a partial, cross-sectional view of the attachment features of the casing components 106, 108 of the disclosed impingement sleeve 102.

The disclosed impingement sleeve 102 may generally be configured to be positioned radially outwardly from the inner duct 104 of the transition piece 100. For example, the impingement sleeve 102 may be disposed relative to the inner duct 104 such that a radial space or gap 110 is defined between the impingement sleeve 102 and the inner duct 104. As such, the pressurized air discharged from the compressor section 12 of the gas turbine 10 (FIG. 1) may be directed through the radial gap 110 to provide cooling for the inner duct 104. For instance, a plurality of cooling holes 112 may be defined through the impingement sleeve 102 such that the pressurized air flowing along its outer perimeter may be directed through the impingement sleeve 102 and may impinge onto the outer surface 114 of the inner duct 104. Additionally, as is generally understood, the downstream ends 116 of the impingement sleeve 102 and/or the inner duct 104 may be configured to be coupled to a downstream component of the gas turbine 10, such an aft frame 42 of the combustor 20 (FIG. 2).

As shown in the illustrated embodiment, the impingement sleeve 102 includes a first casing component 106 and a second casing component 108. The first and second casing components 106, 108 may generally define a shape or profile corresponding to the shape or profile of the portion of the inner duct 104 around which the casing components 106, 108 are configured to be disposed (e.g., the first and second side portions 118, 120 of the inner duct 104). However, it should be appreciated that the shape or profile of the first and second casing components 106, 108 may also be varied from the shape or profile of the inner duct 104 to take into account effective cooling configurations and the available packaging within the gas turbine 10.

In general, the first and second casing components 106, 108 may be configured to be attached to another such that, once assembled, the casing components 106, 108 generally encase the inner duct 104. Thus, as shown, an attachment joint 140 may generally be formed at the interfaces of the first and second casing components 106, 108, such as between the top ends 126 of the casing components 106, 108 and between the bottom ends 128 of the casing components 126, 128. It should be appreciated that the casing components 106, 108 may generally have any suitable configuration designed to form any suitable joint known in the art. However, in several embodiments of the present subject matter, the casing components 106, 108 may be configured to overlap one another such that the attachment joints 140 defined between the casing components 106, 108 are configured as lap joints.

For example, in the illustrated embodiment, the first casing component 106 may include a first mounting flange 122 disposed at a top end 126 of the casing component 106 and a second mounting flange 124 disposed at a bottom end 128 of the casing component 106. Similarly, the second casing component 108 may include a first mounting shoulder 130 disposed at a top end 126 of the casing component 108 and a second mounting shoulder 132 disposed at a bottom end 128 of the casing component 108. The flanges 122, 124 and shoulders 130, 132 of the casing components 106, 108 may generally be configured such that, when the first and second casing components 106, 108 are assembled around the inner duct 104, the first shoulder 130 is aligned with and overlaps the first flange 122 and the second shoulder 132 is aligned with and overlaps the second flange 124 so as to define the attachment joints 140. The flanges 122, 124 and shoulders 130, 132 may then be attached to one another such that the first and second casing components 106, 108 generally form an encasing configuration about the inner duct 104.

In several embodiments, to facilitate the overlapping configuration of the casing components 106, 108, the second casing component 108 may include a slight bend at the attachment joints 140 having a height generally equal to the width 143 (FIG. 6) of the flanges 122, 124 to permit the shoulders 130, 132 to be aligned with and overlap the flanges 122, 124. Specifically, as shown in FIG. 6, the second casing component 108 may include a radially outwardly extending bend 142 at the base of each shoulder 130, 132 such that the flanges 122, 124 may be disposed radially inwardly from the shoulders 130, 132. Alternatively, the second casing component 108 may include a radially inwardly extending bend 142 at the base of each shoulder 130, 132 such that the flanges 122, 124 may be disposed radially outwardly from the shoulders 130, 132. In other embodiments, it should be appreciated that the second casing component 108 need not define a bend 142. For example, in one embodiment, the second casing component 108 may simply define a radius of curvature or may otherwise have a radial dimension which is slightly larger or slight smaller than the radius of curvature or radial dimension of the first casing component 106 such that the flanges 122, 124 and shoulders 130, 132 overlap one another when the casing components 106, 108 are positioned together.

Additionally, in several embodiments of the present subject matter, the attachment joints 140 may generally be configured as substantially flat joints. By “substantially flat”, it is meant that the shape or profile of the portions of the casing components 106, 108 forming the attachment joints 140 may generally correspond to the overall shape or profile of the impingement sleeve 102 in an area generally adjacent to the joints 140. For example, the flanges 122, 124 and the shoulders 130, 132 may generally be configured to form an extension of the shape or profile of the first and second casing components 106, 108, respectively, at each attachment joint 140. Thus, as shown in FIGS. 3-4 and 6, the first and second flanges 122, 124 may generally define a straight or curved profile extending substantially tangentially and/or parallel to the profile of the first casing component 106 in an area adjacent to the attachment joint 140 (e.g., the profile defined at the top and bottom ends 126, 128 of the first casing component 106). Similarly, the first and second shoulders 130, 132 may generally define a straight or curved profile extending substantially tangentially and/or parallel to the profile of the second casing component 108 in an area adjacent to the attachment joints 140 (e.g., the profile defined at the top and bottom ends 126, 128 of the second casing component 108). Additionally, as shown, the flanges 122, 124 and shoulders 130, 132, when attached, may be configured to extend substantially parallel to one another. As such, when the first and second casing components 106, 108 are positioned in an encasing configuration around the inner duct 104, the attachment joints 140 may generally have a substantially flat configuration with respect to the overall shape or profile of the impingement sleeve 102.

It should be appreciated that, in embodiments in which the attachment joints 140 are configured as substantially flat joints, the corresponding profiles of the flanges 122, 124 and shoulders 130, 132 may generally vary depending on the location at which the attachment joints 140 are defined along the outer perimeter of the impingement sleeve 102. For example, in an alternative embodiment, the first and second casing components 106, 108 may be configured such that the attachment joints 140 are defined along the sides 141 of the impingement sleeve 102. In such an embodiment, the flanges 122, 124 and shoulders 130, 132 may generally define a straight or curved profile extending substantially tangentially and/or parallel to the profile of the sides 141 of the first and second casing component 106, 108.

Referring still to FIGS. 3-6, the casing components 106, 108 may generally be configured to be secured to one another at the attachment joints 140 using any suitable means. However, in several embodiments of the present subject matter, the casing components 106, 108 may be configured to be weldlessly attached to one another. For example, in the illustrated embodiment, the first and second flanges 122, 124 may define a plurality of flange openings 134 forming a bolt hole pattern which generally corresponds to the bolt hole pattern formed by a plurality of shoulder openings 136 defined in first and second shoulders 130, 132. Specifically, each of the flange openings 134 defined in the first mounting flange 122 may be configured to be aligned with one of the shoulder openings 136 defined in the first mounting shoulder 130 when the first and second casing components 106, 108 are positioned around the inner duct 104. Similarly, each of the flange openings 134 defined in the second mounting flange 124 may be configured to be aligned with one of the shoulder openings 136 defined in the second mounting shoulder 132. Accordingly, the flange openings 134 and the shoulder openings 136 may generally be configured such that a fastener 138 may be disposed through the aligned openings 134, 136 in order to permit the first casing component 106 to be attached to the second casing component 108.

In general, the disclosed fasteners 138 may comprise any suitable fasteners known in the art. For instance, in several embodiments, the fasteners 138 may comprise a plurality of threaded fasteners, such as threaded bolts, screws and the like. In alternative embodiments, the fasteners 138 may comprise rivets, pins, clips, bolts, brackets, rods and any other suitable mechanical fasteners and/or attachment mechanisms. Additionally, the fasteners 138 may be configured to be secured within the openings 134, 136 using any suitable means. For example, the fasteners 138 may be secured within the openings 134, 136 using nuts, retaining pins, retaining rods, adhesives, and the like. However, in a particular embodiment of the present subject matter, each of the fasteners 138 may be secured within the openings 134, 136 using a floating nut 144.

As is generally understood, a floating nut 144 may comprise a threaded nut 146 which is movably disposed within a cage, frame or other retainer 148. For example, as shown in FIG. 6, the threaded nut 146 may be disposed within the retainer 148 such that a gap is defined between the threaded nut 146 and the base 152 of the retainer 148. As such, the threaded nut 146 may move or otherwise float relative to the retainer base 152 within such gap. Moreover, in addition to being capable of moving towards and away from the retainer base 152, the threaded nut 146 may also be configured to move or otherwise float perpendicularly to retainer base 152. As such, the threaded nut 146 may be displaced or may otherwise be moved into alignment with the fastener 138 as it is inserted through the openings 134, 136. Accordingly, each floating nut 144 may generally provide built-in flexibility in attaching the fasteners 138 to the threaded nuts 146, thereby simplifying the blind attachment of the flanges 122, 124 to the shoulders, 130, 132. It should be appreciated that the floating nuts 144 described herein may generally have any suitable floating nut configuration known in the art and, thus, need not have the exact configuration illustrated herein and described above.

In several embodiments, a plurality of floating nuts 144 may be mounted within the impingement sleeve 102 such that, when the first and second casing components 106, 108 are positioned around the inner duct 104, one floating nut 144 is generally aligned with each pair of aligned flange and shoulder openings 134, 136. For instance, as shown in FIGS. 5 and 6, the floating nuts 140 may be disposed along the inner surfaces 154 of the first and second flanges 122, 124. Alternatively, in embodiments in which the shoulders 130, 132 are disposed radially inwardly from the flanges 122, 124, the floating nuts 144 may be disposed along the inner surfaces 156 (FIG. 6) of the first and second shoulders 130, 132.

Additionally, in one embodiment, each of the floating nuts 144 may be separately mounted onto an inner surface of the impingement sleeve 102, such as the inner surfaces 154 of the flanges 122, 124. For example, the retainer 148 of each floating nut 144 may be directly attached to the inner surfaces 154 of the flanges 122, 124 (e.g., by welding or otherwise fastening the retainer 148 to the inner surfaces 154). Alternatively, the floating nuts 144 may be grouped or ganged into a common carriage or channel 158, 160 for attachment to the inner surfaces 154 of the mounting flanges 122, 124. For instance, as shown in the illustrated embodiment, first and second elongated channels 158, 160 may generally be secured to the inner surfaces 154 of the first and second flanges 122, 124, respectively, such as by welding or otherwise fastening the elongated channels 158, 160 onto the inner surfaces 154.

In several embodiments, each elongated channel 158, 160 may generally be configured to define a shape or profile corresponding to the shape or profile of the portion of the impingement sleeve 102 to which it is attached. Thus, in the illustrated embodiment, the first elongated channel 158 may generally extend lengthwise between the upstream and downstream ends 162, 164 (FIG. 5) of the first flange 122 and may include a base 180 defining a curved profile generally corresponding to the curved profile of the first flange 122. Similarly, the second elongated channel 160 may generally extend lengthwise between the upstream and downstream ends 166, 168 (FIG. 5) of the second flange 124 and may include a base 180 defining a curved profile generally corresponding to the curved profile of the second flange 124. As such, the elongated channels 158, 160 may generally be secured substantially flush against the inner surfaces of the impingement sleeve 102.

It should be appreciated that, in alternative embodiments, the elongated channels 158, 160 need not be configured to extend fully between the upstream and downstream ends 162, 164, 166, 168 of the first and second flanges 122, 124. For example, the elongated channels 158, 160 may only extend partially between the upstream and downstream ends 162, 164, 166, 168. In other embodiments, two or more elongated channels 158, 160 may be secured between the upstream and downstream ends 162, 164, 166, 168 of each flange 122, 124.

Moreover, as shown in FIGS. 3 and 5-6, each elongated channel 158, 160 may generally include a plurality of floating nuts 144 mounted to the base 180 of each channel 158, 160. For example, in one embodiment, the retainers 148 of the floating nuts 144 may be welded or otherwise fastened to each base 180. Additionally, it should be appreciated that the spacing of the floating nuts 144 along each channel 158, 160 may generally correspond to the spacing of the flange and shoulder openings 134, 136 defined in the flanges 122, 124 and the shoulders 130, 132, respectively. Thus, when the elongated channels 158, 160 are secured to the inner surfaces 154, 156 of one of the casing components 106, 108 and the casing components 106, 108 are positioned around the inner duct 104, one floating nut 144 may generally be disposed in alignment with each pair of aligned flange and shoulder openings 134, 136.

It should be appreciated that, in further embodiments, a plurality of threaded members, such as threaded nuts 146, may be secured to the elongated channels 158, 160 as an alternative to the floating nuts 144. Additionally, as particularly shown in FIGS. 3 and 6, in one embodiment, the elongated channels 158, 160 may be configured to include sidewalls 161 extending substantially perpendicularly from the base 180 of each channel 158, 160. Alternatively, the elongated channels 158, 160 may be configured simply as mounting plates and, thus, need not include the illustrated sidewalls 161.

It should also be appreciated that, as an alternative to using fasteners 138 and floating nuts 144 (or threaded nuts 146), various other suitable attachment methods may be utilized to weldlessly attach to the first and second flanges 122, 124 to the first and second shoulders 130, 132. For example, the flanges 122, 124 and the shoulders 130, 132 may be crimped together or attached together using an adhesive or other suitable bonding material.

The first and second casing components 106, 108 may also include corresponding pairs of lips 170, 172 extending radially outwardly from the casing components 106, 108 at their upstream ends 162, 166. In general, the radially extending lips 170, 172 may be configured such that, when the lips 170 of the first casing component 106 are secured to the lips 172 of the second casing component 108, a seal 174 (FIG. 5) disposed between an upstream component 176 of the combustor 20 (FIG. 1) and the upstream ends 162, 166 of the casing components 106, 108 is properly engaged and/or a sufficient force is applied at the interface Additionally, in several embodiments of the present subject matter, the orientation of the radially extending lips 170 of the first casing component 106 may be configured to match or correspond to the orientation of the radially extending lips 172 of the second casing component 108, such as by configuring the lips 170, 172 to extend substantially parallel to one another when the first and second casing components 106, 108 are positioned together. Further, in one embodiment, each of the radially extending lips 170, 172 may be configured to extend substantially perpendicularly from the top and bottom ends 126, 128 of the casing components 106, 108. In other embodiments, it should be appreciated that the lips 170, 172 may generally extend outwardly from the top and bottom ends 126, 128 of the casing components 106, 108 at any suitable angle.

It should also be appreciated that the lips 170 of the first casing component 106 may generally be configured to be attached to the lips 172 of the second casing component 108 using any suitable means. For instance, in the illustrated embodiment, the lips 170, 172 may define openings 178 configured to receive suitable fasteners 179 (e.g., bolts, screws, rivets, pins, other mechanical fasteners and the like) for attaching the lips 170, 172 to one another. Alternatively, various other suitable attachment methods may be utilized to attach to the lips 170, 172 to one another, such as by crimping the lips 170, 172 together or by attaching the lips 170, 172 together using an adhesive or other bonding material.

It should be readily appreciated by those of ordinary skill in the art that, in addition to the configurations described herein, various other impingement sleeve configurations may be utilized within the scope of the present subject matter. For example, the one or more shoulders 130, 132 may be disposed on the first casing component 106 while one or more flanges 122, 124 may be disposed on the second casing component 108. Additionally, as noted above, the flanges 122, 124 need not be disposed radially inwardly of the shoulders 130, 132. Specifically, in several embodiments, the shoulders 130, 132 may be disposed radially inwardly of the flanges 122, 124. In another embodiment, the first shoulder 130 may be configured to be disposed radially inwardly of the first flange 122 while the second shoulder 132 may be configured to be disposed radially outwardly of the second flange 124.

Moreover, it should be appreciated that the first and second casing components 106, 108 need not be configured such that the attachment joints 140 defined at the flanges 122, 124 and the shoulders 130, 132 are formed at the top and bottom ends 26, 128 of the impingement sleeve 102. Rather, the casing components 106, 108 may be configured such that the attachment joints 140 are formed at any location along the outer perimeter of the impingement sleeve 102, such as on the sides 141 or corners of the impingement sleeve 102. Further, in another embodiment, the impingement sleeve 102 may include more than two casing components. For instance, the impingement sleeve 102 may include three or more casing components, with the casing components being configured to be attached to one another so as to encase the inner duct 104.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. An impingement sleeve for a transition piece of a gas turbine, the impingement sleeve comprising: a first casing configured to surround a portion of an inner duct of the transition piece; a second casing configured to surround a portion of the inner duct; and a substantially flat joint defined between said first and second casings, said substantially flat joint including a plurality of fasteners configured to attach said first casing to said second casing.
 2. The impingement sleeve of claim 1, wherein said substantially flat joint is configured as a lap joint.
 3. The impingement sleeve of claim 1, wherein said first casing includes at least one flange and said second casing includes at least one shoulder, said at least one flange being attached to said at least one shoulder at said substantially flat joint.
 4. The impingement sleeve of claim 3, wherein said at least one flange and said at least one shoulder each define a plurality of openings, said plurality of openings being configured to receive said plurality of fasteners.
 5. The impingement sleeve of claim 3, wherein said at least one flange is disposed substantially parallel to said at least one shoulder at said substantially flat joint.
 6. The impingement sleeve of claim 3, wherein at least one of said at least one flange and said at least one shoulder is configured to extend substantially tangent to a profile of the impingement sleeve at said substantially flat joint.
 7. The impingement sleeve of claim 1, further comprising a plurality of threaded nuts mounted to an inner surface of at least one of said first casing and said second casing, said plurality of fasteners comprising a plurality of threaded fasteners being configured to be secured within said plurality of threaded nuts.
 8. The impingement sleeve of claim 7, wherein each of said plurality of threaded nuts is configured as a floating nut.
 9. The impingement sleeve of claim 7, wherein said plurality of threaded nuts is grouped within at least one channel mounted to said inner surface.
 10. The impingement sleeve of claim 9, wherein a profile of said at least one channel is configured to generally correspond to a profile of said inner surface such that said at least one channel is positioned substantially flush against said inner surface.
 11. The impingement sleeve of claim 1, wherein said first casing includes at least one lip extending substantially perpendicularly from an end of said first casing and said second casing includes at least one lip extending substantially perpendicularly from an end of said second casing, said at least one lip of said first casing being configured to be attached to said at least one lip of said second casing.
 12. An impingement sleeve for a transition piece of a gas turbine, the impingement sleeve comprising: a first casing configured to surround a portion of an inner duct of the transition piece; a second casing configured to surround a portion of the inner duct; a joint defined between said first and second casings, said joint including a plurality of threaded fasteners configured to attach said first casing to said second casing; and at least one channel mounted to an inner surface of at least one of said first casing and said second casing, said at least one channel including a plurality of threaded nuts attached thereto.
 13. The impingement sleeve of claim 12, wherein said joint is configured to be substantially flat.
 14. The impingement sleeve of claim 12, wherein said first casing includes at least one flange and said second casing includes at least one shoulder, said at least one flange being attached to said at least one shoulder at said joint.
 15. The impingement sleeve of claim 14, wherein said at least one flange and said at least one shoulder each define a plurality of openings, said plurality of openings being configured to receive said plurality of fasteners.
 16. The impingement sleeve of claim 14, wherein said at least one flange is disposed substantially parallel to said at least one shoulder at said joint.
 17. The impingement sleeve of claim 14, wherein at least one of said at least one flange and said at least one shoulder is configured to extend substantially tangent to a profile of the impingement sleeve at said joint.
 18. The impingement sleeve of claim 12, wherein each of said plurality of threaded nuts is configured as a floating nut.
 19. The impingement sleeve of claim 12, wherein a profile of said at least one channel is configured to generally correspond to a profile of said inner surface such that said at least one channel is positioned substantially flush against said inner surface.
 20. The impingement sleeve of claim 12, wherein said first casing includes at least one lip extending substantially perpendicularly from an end of said first casing and said second casing includes at least one lip extending substantially perpendicularly from an end of said second casing, said at least one lip of said first casing being configured to be attached to said at least one lip of said second casing. 